1. Field of the Invention
The present invention relates to an actuator drive controller, and more particularly, for example, to the actuator drive controller used for controlling an actuator for an automobile such as the actuator of an active control engine mount.
2. Description of the Related Art
Conventionally, there is known an active control engine mount that cancels an uncomfortable vibration for a driver by expecting a vibration input of an engine from a crank pulse and actively controlling vibration absorption characteristics of the engine mount that is arranged so as to support the engine (for example, see paragraphs 0009 to 0019 and FIG. 1 of Japanese Patent Laid-Open Publication 2000-27933). The active control engine mount is composed of a mount part for supporting the engine and an actuator arranged at a lower portion of the mount part. In the active control engine mount the actuator is designed to generate such a vibration that cancels the vibration of the engine. And the vibration generated by the actuator is transmitted to the mount part, and thereby the vibration of the engine is cancelled.
Generally, with such an actuator a voltage applied to it is increased by a voltage boost circuit in order to improve various performances of the active control engine mount. In addition, the voltage boost circuit is designed to increase a current in order to assure a voltage boost performance when a voltage of a power source of the actuator becomes not more than (≦) a predetermined value.
Meanwhile, because a battery voltage lowers with such an actuator drive controller as described above, a current increases by the voltage boost circuit therefore, something, which can endure a larger current, as electric contact points such as a terminal of the voltage boost circuit and circuit components such as a harness and a fuse, becomes necessary. Accordingly, there occurs a problem that the actuator drive controller is enlarged and production cost becomes high. Consequently, it can be considered to provide another actuator drive controller which controls the current so as not to exceed a predetermined value by monitoring the current entering the voltage boost circuit. However, because in the actuator drive controller the voltage boost circuit becomes complex, problems such as the enlargement of the controller and the high cost are not solved. In addition, if the current supplied to the actuator is controlled like the actuator drive controller depending on the monitored current, the current supplied to the actuator is determined regardless of a movement of the actuator. That is, the actuator drive controller cannot accurately control the current supplied to the actuator.
Consequently, a desideratum remains in the art for an actuator drive controller that can accurately control the current supplied to the actuator, and is also inexpensive to manufacture and miniature in size.
The inventor has achieved the present invention not by conventionally monitoring a current when a voltage of a power source lowers, but based on knowledge that the problem described above can be solved by regulating consumption power of an actuator itself and thus controlling the current.
According to a first aspect of the present invention for solving the problem, there is provided an actuator drive controller that comprises a power source which supplies power to an actuator; a voltage detector which detects a voltage of the power source; and a control means for controlling a current supplied to the actuator, based on the voltage detected by the detector, wherein when the voltage becomes not more than (≦) a reference value set in advance, the control means controls the current supplied to the actuator so as to be lower than another current set in advance, depending on consumption power of the actuator, in a case that the consumption power of the actuator is not less than (≧) a specified value set in advance.
In the actuator drive controller the voltage of the power source of the actuator is detected by the voltage detector. On the other hand, based on the detected voltage, the control means determines whether or not the voltage of the power source becomes not more than (≦) the reference value set in advance. And the controller determines whether or not the consumption power of the actuator is not less than the specified value set in advance. Then, when determining that the consumption power of the actuator is (≧) not less than the specified value set in advance, the controller controls the current supplied to the actuator so as to be lower than the current set in advance, depending on the consumption power of the actuator. In other words, when the consumption power of the actuator is large (when a movement of the actuator is large), the current supplied to the actuator is controlled so as not to flow at not less than an allowable value in a case that the voltage of the power source lowers as described above. Meanwhile, when lowering the current supplied to the actuator, a lowering factor of the current is preferably set so that a performance of the actuator is at least maintained at a lowest operable limit therefor.
In addition, in the actuator drive controller the actuator may be driven by a duty ratio set in advance. Furthermore, in the actuator drive controller, when the voltage of the power source is not more than the reference value and the consumption power is not less than the specified value, the controller may be designed to control or change the duty ratio and thereby regulate the current.
According to a second aspect of the present inventions, in the actuator drive controller described in the first aspect the control means controls the current supplied to the actuator, based on the duty ratio set in advance depending on the consumption power of the actuator; and when the voltage is not more than the reference value and the consumption power of the actuator is not less than the specified value, the control means controls the current supplied to the actuator so as to become smaller than the duty ratio set in advance, based on a compensation duty ratio that is compensated.
In accordance with the actuator drive controller described in the first aspect, when the voltage of the power source lowers, the controller can be made to control the current so as not to exceed the predetermined value, for example . Therefore, something which can endure a larger current, as electric contact points such as a terminal of a voltage boost circuit and circuit components such as a harness and a fuse, is not required. In addition, because it is not required to monitor a current that is input to the voltage boost circuit, the controller does not become complex. Accordingly, in accordance with the present invention described in the first aspect an inexpensive and miniature actuator drive controller can be provided.
In addition, in accordance with the actuator drive controller, because when the voltage of the power source becomes not more than the reference value and the consumption power of the actuator is not less than the specified value, the current can be regulated by lowering the consumption power of the actuator itself, the current supplied to the actuator can be more accurately controlled.
In accordance with the actuator drive controller described in the second aspect of the invention, because the current is controlled, based on the duty ratio set in advance depending on the consumption power of the actuator, the current supplied to the actuator can be accurately controlled, depending on the movement of the actuator.